Various wind power generation systems, i.e., windmill-type electric generation systems have been proposed. One of the conventional windmill-type electric generation systems is described in the specification of Korean Patent Application No. 2000-76789, which is related to the present invention.
This conventional windmill-type electric generation system includes rotary shafts coaxially mounted through a housing, first and second rotary blade units mounted to the corresponding rotary shafts in front of the housing such that the first and second rotary blade units can be rotated in opposite directions, and first and second electric generators for generating electricity by using the rotating force of the first and second rotary blade units. The conventional windmill-type electric generation system with the above-stated construction has advantages in that the two rotary blade units, i.e., the first and second rotary blade units, are mounted for a single housing, and the amount of electricity generated is doubled by using the two electric generators. However, the conventional windmill-type electric generation system has drawbacks in that the costs necessary for installing the windmill-type electric generation system are increased due to the provision of the plurality of electric generators, and it is difficult to maintain the windmill-type electric generation system.
Another windmill-type electric generation system is described in the specification of Korean Patent Application No, 2002-12965, which was filed in Korean Intellectual Property Office on May 11, 2002. This conventional windmill-type electric generation system is characterized in that rotating forces of two blade units are transmitted to a magnetic pole and an armature of an electric generator in opposite directions, whereby the electricity generation efficiency is doubled while the windmill-type electric generation system is easily and conveniently maintained. In case of every windmill-type electric generation system, it is required that the windmill, i.e., the rotary blade units, faces toward the blowing direction of wind. To this end, a rudder is further included in the conventional construction as in the conventional windmill-type electric generation system described in the specification of the above-mentioned patent application. In this case, however, it is difficult to adjust the directions of the rotary blade units such that the rotary blade units face toward the blowing direction of wind. Furthermore, the rotating force is not generated by the two rotary blade units when the wind blows gently